Zelada would neither confirm nor deny comments made Monday by Haroldo Lima, the head of Brazil's National Petroleum Agency, or ANP, that the new discovery could contain reserves of up to 33 billion barrels of oil equivalent, or BOE.

"There's nothing concrete in those estimates," Petrobras Exploration Director Guilherme Estrella Tuesday told a Senate commission in Brasilia later Tuesday, according to the Estado newswire. "Petrobras works with technical data and concrete estimates."

Zelada said the new oil find is within the BM-S-9 exploration block. He added that Petrobras is calling the find Carioca.

There was some confusion as to which find Lima was referring to Monday after he called it both Carioca and Pao de Acucar - or Sugar Loaf in English.

There was also confusion as to whether the find extended beyond the BM-S-9 block.

Lima reportedly said Tuesday that the information he gave Monday was based on an article published in World Oil Magazine in February. The article called the discovery 'Carioca-Sugar Loaf,' and said it extended from the BM-S-9 block to the adjacent BM-S-8 block, and possibly also into the adjacent BM-S-21 and BM-S- 22 blocks.

In a report issued Monday, Credit Suisse said Sugar Loaf is one large structure that contains all four blocks, while Carioca is one oil find within that structure, next to other finds.

Credit Suisse, however, cautioned that drilling in the Sugar Loaf area "has been very limited to date," and said that therefore markets may have overreacted to Lima's comments.

"We currently include 15 billion BOE of Blue Sky resource in our estimates for the licensed part of Sugar Loaf," the report said, adding that around 40% of the estimated area is still unlicensed.

The BM-S-9 block is operated by Petrobras with a 45% stake, while BG Group ( BRGYY) holds 30% and Repsol YPF SA (REP) holds 25%.

A spokesman for BG Group declined to comment on the size of the reserves in the Carioca find. He said stakeholders in the field would be putting together a plan to evaluate the size of the resources in Carioca in the next few days.

Repsol said in a filing Tuesday to the Spanish market regulator that comments made by Brazil's National Petroleum Agency and Petrobras were accurate, and a spokesman added that time was needed to analyze drilling results.

Both BG's and Repsol's shares also soared Tuesday.

The BM-S-8 block is operated by Petrobras with a 50% stake. Royal Dutch Shell PLC (RDSA) has a 40% stake and Portugal's Galp Energia (GALP.LB) 10%.

The BM-S-21 block is operated by Petrobras with an 80% stake, while Galp Energia holds 20%. The BM-S-22 block is operated by ExxonMobil Corp. (XOM) with a 40% stake, while Hess Corp. (HES) holds 40% and Petrobras 20%.

Exxon and Hess said they plan to drill a first well in the BM-S-22 block this year.

Zelada also said Tuesday that if massive discoveries in Brazil's promising pre-salt area were to be confirmed, the company may have to shift resources away from overseas operations into Brazil.

Petrobras currently is expanding its overseas activities and plans to invest $ 15 billion outside Brazil from 2008 through 2012, he said.

In November, the company said it estimated recoverable reserves at its Tupi field in the pre-salt area of up to 8 billion barrels of oil equivalent.

Reserves for the entire pre-salt area are much larger than the Tupi field, and could put Brazil between Nigeria and Venezuela in terms of oil reserves, Petrobras Chief Executive Sergio Gabrielli said in November.

In January 2007, Nigeria had 36 billion barrels in proven oil in reserves, Venezuela had 80 billion barrels and Brazil had 12 billion barrels, according to the Oil and Gas Review.

Petrobras has said that reserves in the pre-salt area lie at a water depth of about 2,000 meters, and then a further 5,000 meters below a layer of sand, rocks and salt.